1. Field of the Invention
The present invention relates to a magnetic shielding package structure of a magnetic memory device, and more particularly to a magnetic shielding package structure of a wafer-level magnetic memory device.
2. Description of the Related Art
The principles adopted in the application of magnetic memory device are similar to those in the hard disk, while the fabrication thereof is highly compatible with the semiconductor processing and the operating speed thereof is substantially comparable with that of the static random access memory (SRAM). Moreover, the magnetic memory device is basically constructed by a transistor and a magneto-resistor for memory, which is similar to the existing dynamic random access memory (DRAM), and hence the fabrication cost therefor is possibly parallel with that for the existing DRAMs. The magnetic memory device exhibits the advantages of existing memories or storage devices such as the high density hard disk (HDD), flash memories, SRAMs and DRAMs, and is thus regarded as a next-generation memory technique of great potential in replacing the existing ones. It is typically believed that since the magnetic memory device adopts the magnetic material as the core unit for memory, the operation thereof may be inversely affected and the data storage thereof may be inaccurate or even disappear when such device is suffering the disturbance caused by an external magnetic field. Accordingly, the package for the magnetic memory device shall be well designed and constructed so as to prevent the data storage thereof from being erroneous or disappeared due to the disturbance caused by the external magnetic field while in use.
It is found that U.S. Pat. No. 6,967,390 discloses a package structure for leadframe, which adopts a magnetic shielding carrier therein but possesses a relatively inferior ability in magnetic shielding. Moreover, U.S. Pat. No. 4,953,002 also discloses a package structure for leadframe in which the magnetic shield is provided respectively above and below the die within the molding layer. Nevertheless, such package structure lacks the capacity of magnetic shielding. With regard to the package structure for leadframe as disclosed in U.S. Pat. No. 5,939,772, a magnetic shield is respectively attached to the upper side as well as the lower side of package structure, by which the magnetic shielding is still difficulty achieved, however. A further kind of package structure for flip-chip is disclosed by respective U.S. Pat. Nos. 6,559,521, 6,664,613 and 6,717,241, in which the interposer and the printed circuit board thereof include respective protection layers for magnetic shielding. Nevertheless, it is believed only the backside of such package structure could exhibit the ability in magnetic shielding and the efficiency thereof is relatively low. Referring to the respective disclosures of U.S. Pat. No. 6,962,833 as well as U.S. Pub. Nos. 20040119095 and 20060019422, a package structure for leadframe is provided with the magnetic shield respectively attached to the upper and lower sides of the molding layer thereof. By such structure, however, it still fails to achieve the purpose of magnetic shielding. As to the package structure for flip-chip as disclosed in U.S. Pub. No. 20040150091, the magnetic shielding effect is not induced thereby even though such structure adopts a molding layer of magnetic shielding characteristic and an interposer containing magnetic shielding materials. In U.S. Pub. No. 20060180880, a package structure for flip-chip is provided. The package structure is constructed by a composite of two different magnetic shielding materials, but the magnetic shielding effect is only realized on the upper surface and both sides thereof, which is relatively low. With reference to U.S. Pub. No. 20060289970, it is disclosed that the whole circuit module is contained within a magnetic shielding metal house. In this case, however, the module itself possesses no ability in magnetic shielding.
Based on the above, it is desired to provide a further magnetic shielding package structure, which provides the magnetic shielding effect and thereby the magnetic memory device is protected.